A student's high school essay detailing the sexual abuse she and her siblings faced led to the conviction of the man who raped them

Anthony Knight, 43, was sentenced to 20 years in prison last week after pleading guilty to felony charges of rape in Fremont, Ohio.

His sentence came after a high school student detailed the sexual abuse she and her siblings faced in an essay.

Knight had sexually assaulted the girl and her two sisters for multiple years, starting when the youngest was seven years old.

A girl's high school essay that uncovered the sexual abuse she and her sisters faced led to the conviction of the man who raped them.

Anthony Knight, 43, was sentenced to 20 years in prison last week after pleading guilty to felony charges of rape in Fremont, Ohio.

Anthony Knight Sandusky County Sheriff's Office An investigation began after school officials at Vanguard Tech Center alerted child services and the sheriff's office, about the essay, according to the Associated Press.

"The class was asked, I believe, to write an essay pertaining to obstacles that they had overcome in their life and she had disclosed that she had been sexually abused as a child," Detective Sergeant Kenneth Arp, of the Sandusky County Sheriff's Office, told WTOL.

Knight had sexually assaulted the three siblings for multiple years, starting when the youngest was seven years old.

Knight was indicted on 12 counts of rape, but he only pleaded guilty to three on Tuesday.

While the rapes happened years ago, officials said they just learned of the abuse through the teenage girl's school essay.

The girls said they were reluctant to come forward because they had not reported the abuse in the past.

The victims' names have not been made public for their safety and protection.

"I think that these types of things happen a lot more often then what the average person might think that it does," Arp told WTOL. "I think that if you talk to different investigators around the area they will tell you that they work a lot of sexual assault cases similar to this. This one happens to have a positive outcome and unfortunately a lot don't, but I think it sends a great message."

If you are a victim of sexual assault, you can visit RAINN or call its hotline at 1-800-656-4673 to receive confidential support from a trained staff member.